[workflow] add experimental AUR release workflow

OK, so I don't know how to test this, but *theoretically*, this should
automatically push releases to AUR.

.github/workflows/aurpublish.yml

@@ -0,0 +1,29 @@
+---
+name: Upload AUR Package
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  aur-publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install requests
+      - name: Create PKGBUILD
+        run: |
+          python ./create-pkgbuild.py > ./PKGBUILD
+      - name: Publish AUR package
+        uses: KSXGitHub/github-actions-deploy-aur@v2.5.0
+        with:
+          pkgname: bumblebee-status
+          pkgbuild: ./PKGBUILD
+          commit_username: ${{ secrets.AUR_USERNAME }}
+          commit_email: ${{ secrets.AUR_EMAIL }}
+          ssh_private_key: ${{ secrets.AUR_SSH_PRIVATE_KEY }}
+          commit_message: Update AUR package
+          ssh_keyscan_types: rsa,dsa,ecdsa,ed25519